City of Pendleton – Wastewater Treatment Plant Improvements Phase 1 Upgrades, Schedule B – Outfall

The project included the construction of a new sewer discharge outfall into the Umatilla River.  Construction included installation of a new 96”diversion manhole over the existing outfall alignment.  Modifications were made to three existing sewer manholes.  Installation of dual 14” ductile iron inverted siphons and electrical conduits installed under McKay creek.  Installation of 1,150 LF of new 24”PVC outfall piping and a new 16” ductile iron reinforced concrete encased outfall within the Umatilla River.  This outfall extended over 35’ into the river and required solid rock excavation for placement.  Construction of the outfall piping included drilling rebar anchors 10’ deep in solid rock to connect to the outfall piping’s concrete encasement.  Construction required work within two water bodies with separate in-water work windows, temporary dam construction, dewatering facilities, floodplain site work modifications and stream bank restoration.  This project was finished under budget and ahead of schedule.

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Owner: City of Pendleton

Engineer: Kennedy/Jenks Consultants

Location: Pendleton, Oregon

Completion Date: 2012